Slip ring assembly

ABSTRACT

A slip ring assembly employs an elongated shaft which has a number of axially extending surface channels about its circumference and which has mounted thereon a number of contact sets consisting of an annular spacer and a contact member. Each contact member has an element projecting into one of the channels and connected to a lead wire seated therein, and each contact member has at least a portion of its external surface partially exposed for electrical contact by an external member.

Dube et al.

[151 3,686,514 [4 1 Aug. 22, 1972 i [72] Inventors:

[ 41 SLIP RING ASSEMBLY Milford J, Dube, Windsor Locks; Robert A. Semrow, Southington, both of Conn.

The J. M. Ney Company, Bloomfield, Conn.

July 16, 1971 731 Assignees Filed:

Appl. No.:

US. Cl. ..3l0/232, 339/5 M Int. Cl. ..H0lr 39/08 References Cited UNITED STATES PATENTS 2,471,808 5/1949 Baker .......310/232 .Fleld of Search ..3l0/232; 339/5 gar .Pandapas... ..310/232 3,042,998

7/ 1962' Sweett .,...339/5 X Primary Examiner-D. X. Sliney Attomey-Peter L. Costas ABSTRACT A slip ring assembly employs an elongated shaft which has a number of axially extending surface channels about its circumference and which has mounted thereon a number of contact sets consisting of an annular spacer and a contact member. Each contact member has an element projecting into one of the channels and connected to a lead wire seated therein, and each contact member has at leasta portion of its external surface partially exposed for electrical contact by an external member.

7 Claim, 3 Drawing Figures Patented Aug. 22, 1912 3,686,514

' 2 Sheets-Sheet 2 In wen furs Mf/ford L/ Dufie Roberf 14- Semraw SLIP RING ASSEMBLY BACKGROUND OF THE INVENTION As is well known, in many different types of electrical and electronic equipment it is necessary to transfer electrical energy between relatively moving members; for example, such a requirement is common in electronic business machines, audio and video equipment, telephone equipment, and the like. In addition, it is frequently necessary to provide a number of contact points at each transfer location, and a variety of different types of slip ring assemblies having such capabilities have been proposed and are presently available. There is a significant demand for moving contact devices having elements which are relatively simple and inexpensive to manufacture and which are adapted for quick and easy assembly. Facility of assembly is of particular importance in producing the miniaturized devices that are now extensively used in much of the sophisticated electronic apparatus. In addition, it is desired to electrical noise and distortion arising from contact between relatively moving parts.

Accordingly, it is an object of the present invention to provide a novel slip ring assembly comprised of relatively few and relatively simple parts which are quickly and easily assembled.

Another object is to provide such an assembly that is especially adapted to the use of contact members affording highly desirable electrical characteristics including substantial freedom from noise and distortion.

A further object of the invention is to provide such a slip ring assembly which is particularly well suited for production in miniature sizes.

SUMMARY OF THE DISCLOSURE It has now been found that the foregoing and related objects of the invention are'readily attained in a slip ring assembly comprising an elongated shaft having a multiplicity of axially extending surface channels spaced about the periphery thereof, and a plurality of lead wires, each seated in and extending along one of the channels. A plurality of substantially identical contact sets are adjacently mounted upon the shaft along the length thereof and over the channels, and each of the contact sets includes a generally annular metallic contact member and a generally annular spacer of insulating material. Each spacer has a spacing portion at one end thereof and a support portion extending axially therefrom about which the contact member extends circumferentially with its exterior surface at least partially exposed for external contact. Each of the contact members has an element extending into one of the plurality of channels and electrically connected to the lead wire seated therein. The spacing portion of the spacer of one of the contact sets extends between the contact member thereof and the contact member of an adjacent contact set to isolate the contact member of one set from that of the adjacent set.

In the preferred embodiments of the invention in each of the contact sets the contact member has a cylindrical portion seated upon the support portion of the spacer, and a tab portion at one end and extending radially inwardly therefrom along and beyond the other end of the spacer and into the associated channel to the contact element thereof. Most desirably, the contact member is fabricated of a wrought gold alloy. The

spacer of each of the contact sets may have a generally cylindrical support portion, and the outer surface of the one end thereof may have an annular,coaxial recess formed therein with the cylindrical other end of the spacer of the adjacent set seated in the recess. Most desirably, the assembly will include at least three contact sets, with the outer end of the cylindrical portion of the contact member of each of the sets having a circumferential lip portion extending radially inwardly thereabout. The lip portion may overlie the other end of the spacer, and that end may be bevelled for a short axial distance to facilitate mounting of the contact member. In assembly, the lip portion of the contact member of one set is seated in the annular recess formed in the one" end of the spacer of an adjacent contact set.

Most desirably, the assembly additionally includes a mounting fixture at one end of the shaft and retaining means at the other end thereof; the fixture and retaining means are affixed to the shaft with the plurality of contact sets secured therebetween. The shaft end mounting fixture may have interengaging means to prevent substantial relative rotation thereof.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view, in partial section, of a slip ring assembly embodying the present invention;

FIG. 2 is an end view of the assembly of FIG. 1; and FIG. 3 is an exploded perspective view thereof.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Turning now in detail to the appended drawing, therein illustrated is a slip ring assembly embodying the present invention and including an elongated cylindrical shaft, generally designated by the numeral 10, having its circumferential surface formed with a multiplicity of axially extending ribs 12 defining channels 14 therebetween. A radially outwardly extending shoulder element 16 is provided on each of the ribs 12 at one end of the shaft 10, and a boss 18 of lesser diameter projects axially from the opposite end thereof.

The assembly also includes a mounting fixture, generally designated by the numeral 20, consisting of a generally cylindrical hub portion 22 with an axial passageway 24 extending therethrough and a radially extending flange 26 extending about the circumference thereof intermediate its ends. The passageway 24 has an enlarged diameter portion at one end to provide an annular shoulder 28 against which the shoulder elements 16 of the shaft 10 seat to prevent passage of the shaft 10 entirely through the mounting fixture 20. A short axially extending rib or key 30 projects radially into the enlarged portion of the passageway 24 from the wall 32 thereabout and, as is best seen in FIG. 2, the key 30 projects into one of the channels 14 so that interference with the adjacent shoulder elements 16 of the shaft 10 prevents rotation thereof relative to the fixture 20. The flange 26 of the fixture 20 has three reinforcing bosses 34 at equidistantly spaced locations thereabout, and a counterbore aperture 36 to receive through the flange 26 within each of the reinforcing bosses 34 to receive mounting fasteners (not shown); a recess 38 is provided in the outer face of the flange 26, and serves an indexing function.

Mounted upon the shaft are a multiplicity of adjacent contact sets, each consisting of an annular spacer and a contact ring, generally designated by the numerals 40 and 42, respectively. All of the spacers 40 and all of the contact rings 42 are essentially identical, and therefore only one of each will be referred to and described.

The spacer 40 has a generally cylindrical hub or support portion 46 with a bevelled or tapered outer surface 48 at one end and a radially extending collar portion 50 at the other end thereof. The collar portion 50 has a circular channel or recess52 formed in its inner surface adjacent the juncture with the hub portion 46 to define the axially inwardly projecting and circumferentially extending lip 51. On its outer surface, the collar portion 50 has an axially outwardly projecting lip 53 extending circumferentially thereabout to define a coaxial annular recess 54 in the outer end of the spacer 40. As can be seen, the circular aperture 44 extending through the hub portion 46 is dimensioned to seat snugly the shaft 10 which extends therethrough.

The contact ring 42 has a generally cylindrical body portion 56 with a radially inwardly extending circumferential lip 58 at one end and a radially outwardly projecting circumferential flange 60 at the opposite end thereof. The ring 42 is mounted upon the spacer 40 with the body portion 56 overlying the support portion 46 of the spacer 40, with the lip 58 extending inwardly along the bevelled end thereof, and with the flange 60 of the ring 42 seated within the channel 52, An L- shaped contact tab 62 projects radially inwardly from the lip 58 of the ring 42 into one of the channels 14 and then extends axially in contact with the stripped end 64 of the lead wire 66, that extends with the channel 14; preferably, the contact tab 62 and lead wire end 64 will be secured together by soldering, brazing, or other appropriate means.

It will be apparent that the channels 14 permit ready alignment of the contact tabs 62 and lead wires 66, thus enabling contact and interconnection thereof and greatly facilitating assembly. After the full complement of contact sets necessary to provide a terminal for each of the lead wires 66 has been stacked upon the shaft 10, and the tab 62 of each of them connected to one of the leads 66, the assembly is completed simply by frictionally engaging the retainer disk 68 upon the boss 18 of the shaft 10 and against the end-most spacer 40. The contact sets are thereby held tightly in place between the retainer disk 68 and the mounting fixture 20 with the lip 58 and adjacent portion of the ring 42 of one set seated in the annular recess 54 of the spacer 40 adjacent thereto. The slip ring assembly may then readily be installed as desired for rotation and wiping contact with a brush assembly or the like (not illustrated) with the indexing bore 38 serving to identify the several leads 66 by reference thereto and with all of the tab/lead wire interconnections lying beneath the rings 42 and thereby protected against inadvertent disassembly by impact thereon.

It will be appreciated that a different number of contact sets and lead wires may be employed in the illustrated embodiment, and that the length and/or the diameter of the shaft (and consequently, the dimensions of the other elements, to be consistent therewith) may b changed to permit the formation of additional or fewer wire-receiving channels about the shaft, as may be necessary. The specific dimensions and configuration of the various parts of the assembly will depend upon numerous factors and will be apparent to those skilled in the art. However, as has been emphasized, the construction herein described lends itself particularly well to miniaturization; for example, overall dimensions of about three-eight inch in diameter (exclusive of the mounting fixture) and less than 1 inch in length are typical in such a miniature assembly. The present construction also permits the ready substitution of a variety of different independent mounting fixtures or elements, further enhancing the flexibility of usage thereof.

Virtually any electrically conducting metal capable of being fabricated in an appropriate configuration may be employed as the contact member including essentially pure metals such as copper, gold, aluminum, silver, etc., and alloys thereof and of other metals such as beryllium-copper, phosphor-bronze, stainless steels, etc. However, in the more sensitive or sophisticated applications where high corrosion resistance, low contact noise and relative freedom from distortion are essential criteria, noble metal alloys of gold, gold-platinum, etc., are especially desirable. It is particularly significant that the construction defined herein is ideally adapted for the use of contact members os wrought precious metal alloys such as the gold alloy sold by The J. M. Ney Company, of Bloomfield, Connecticut, under the trademark NEY-ORO G. Contact members fabricated from such a wrought alloy may have excellent tensile and hardness properties to resist damage in handling and wear in use, even though they are quite small and thin in cross section (as is the case ofminiature assemblies); accordingly, use thereof constitutes a preferred embodiment of the invention.

The choice of materials for use in fabricating the non-conduction portions of the assembly will depend upon the structural and dielectric properties required therein. Included are synthetic plastic materials, ceramics and graphite. Preferred are the synthetic plastics including the phenol-formaldehyde type of thermosetting resins and thermoplastics such as the polycarbonates, the long-chain polyamides, polyesters (e.g., polyethylene terephthalate resins), polyolefins (e.g., polyethylene, polypropylene, etc.), vinyl and vinylidene resins (e.g., polystyrene, polyvinylchloride, styrene/acrylonitn'le copolymers, high impact polystyrene, etc.), and the like.

Thus, it can be seen that the present invention provides a novel slip ring assembly comprised of relatively few and relatively simple parts which are well adapted for rapid and facile assembly, the parts themselves being fabricated readily and relatively economically from materials affording high beneficial properties. As will be appreciated, the channels defined in the elongated shaft serve to readily seat the lead wires and to appropriately position the contact elements of the contact sets, so that they may be stacked upon the shaft quickly and accurately for interconnection of each with a selected lead wire. In addition, the assembly is so constructed as to make the use of electrical contact elements affording highly desirable electrical characteristics, and the assembly is particularly well suited for production in miniature sizes.

Having thus described the invention, we claim:

spacing portion at one end thereof and a support portion extending axially therefrom, said contact member extending circumferentially about said support portion and having its exterior surface at least partially exposed thereon for external contact, and said contact member having a contact element extending into one of said plurality of channels and electrically connected to said lead wire seated therein, said spacing portion of said spacer of one of said contact sets extending between the contact member thereof and the contact member of an adjacent contact set to isolate the contact member of one set from the contact member of the adjacent set.

2. The assembly of claim 1 wherein in each of said contact sets said contact member has a cylindrical portion seated upon said support portion of said spacer and a tab portion at one end extending radially inwardly along and beyond the other end of said spacer into the associated channel to provide said contact element.

3. The assembly of claim 2 wherein said contact member of each of said sets is fabricated from a wrought gold alloy.

4. The assembly of claim 2 wherein said support portion of said spacer in each of said sets is generally cylindrical and wherein the outer surface of said one end of said spacer has an annular, coaxial recess formed therein, the cylindrical other end of the spacer of the adjacent set being seated in said recess.

5. The assembly of claim 4 including at least three contact sets, wherein in each of said sets said outer end of said cylindrical portion of said contact member has a circumferential lip portion extending radially inwardly thereabout, wherein said other end of said spacer is bevelled for a short axial distance to facilitate mounting of said contact member thereon, and wherein said lip portion of said contact member overlies said other end of said spacer, the lip portion of the contact member of one set being seated in the annular recess formed in the one end of the spacer of an adjacent set.

6. The assembly of claim 1 additionally including a mounting fixture at one end of said shaft and retaining means at the opposite end thereof, said fixture and retaining means being affixed to said shaft with said plurality of contact sets secured therebetween.

7. The assembly of claim 6 wherein said shaft and mounting fixture have interengaging means preventing substantial relative rotation thereof. 

1. In a slip ring assembly, the combination comprising: an elongated shaft having a multiplicity of axially extending surface channels spaced about the periphery thereof; a plurality of lead wires, each seated in and extending along one of said channels; and a plurality of substantially identical contact sets adjacently mounted upon said shaft along the length thereof over said channels, each of said contact sets comprising a generally annular metallic contact member and a generally annular spacer of insulating material, said spacer having a spacing portion at one end thereof and a support portion extending axially therefrom, said contact member extending circumferentially about said support portion and having its exterior surface at least partially exposed thereon for external contact, and said contact member having a contact element extending into one of said plurality of channels and electrically connected to said lead wire seated therein, said spacing portion of said spacer of one of said contact sets extending between the contact member thereof and the contact member of an adjacent contact set to isolate the contact member of one set from the contact member of the adjacent set.
 2. The assembly of claim 1 wherein in each of said contact sets said contact member has a cylindrical portion seated upon said support portion of said spacer and a tab portion at one end extending radially inwardly along and beyond the other end of said spacer into the associated channel to provide said contact element.
 3. The assembly of claim 2 wherein said contact member of each of said sets is fabricated from A wrought gold alloy.
 4. The assembly of claim 2 wherein said support portion of said spacer in each of said sets is generally cylindrical and wherein the outer surface of said one end of said spacer has an annular, coaxial recess formed therein, the cylindrical other end of the spacer of the adjacent set being seated in said recess.
 5. The assembly of claim 4 including at least three contact sets, wherein in each of said sets said outer end of said cylindrical portion of said contact member has a circumferential lip portion extending radially inwardly thereabout, wherein said other end of said spacer is bevelled for a short axial distance to facilitate mounting of said contact member thereon, and wherein said lip portion of said contact member overlies said other end of said spacer, the lip portion of the contact member of one set being seated in the annular recess formed in the one end of the spacer of an adjacent set.
 6. The assembly of claim 1 additionally including a mounting fixture at one end of said shaft and retaining means at the opposite end thereof, said fixture and retaining means being affixed to said shaft with said plurality of contact sets secured therebetween.
 7. The assembly of claim 6 wherein said shaft and mounting fixture have interengaging means preventing substantial relative rotation thereof. 